So-called Islamic State (IS) said it was behind the Brussels attacks.
An online statement from the group said the locations were “carefully selected” and warned of worse to come in future.
Belgian police have identified and issued a wanted notice for a suspect after bomb attacks at Brussels’ main airport and a metro station, which left more than 30 people dead. Belgian prosecutor Frederic Van Leeuw said police were looking for a man wearing a hat and light-coloured jacket.
The identified terrorist was seen walking with two other suspects shortly before twin explosions which killed 30 people and left over 90 people wounded.
Both men died in the attacks after detonating suicide devices, a Belgian prosecutor said. He said searches were taking place “in several parts of the country”, adding that an explosive device containing nails, chemical products and an IS flag were found in an apartment in the Schaerbeek area of Brussels.
The raid in Schaerbeek reportedly followed a tip-off from a taxi driver who had driven the three suspected bombers to the airport.
The US State Department has urged US citizens of “potential risks” of travelling to Europe.
“Terrorist groups continue to plan attacks throughout Europe, targeting sporting events, tourist sites, restaurants and transportation,” a statement said.
